Lifting-jack



W. H. FOWKES.

LIFTING JACK. 4unicnlon msn mn. s. |919.

1,396,951 Patented Nov. 15, 1921` ,7 2 sains-'suur 1; 5 66;/

'if i v I /5 w. H. FowKEs.

LIFTING JACK.

APPLICATION FILED MAR. 8, 19,19.

2 SHEETS-S Patented N0v. 15, 1921.

MEET 2.

UNITED STATESA PATENT OFFICE.

WILLIAM HERBERT rowxnsfor CHICAGO, ILLINOIS, AssIGNon r.ro BUDA`ooMrANY,

`A coRPoRA'rIoN or ILLINoIs.

. My invention relates to those liftingiiaclrsf usually designatedin thetrade` as ball'bean ing screw-jacks, and has for `its chief aim ingeneral to improvethe construction and increase the efficiency andutility of jacks of this type, and in particular to produce aquick-raising self-lowering j ack,` the selflowering action of which isautomatic. i

` One of the salient objects kof theinvention is to produce `anautomatic self-lowering jack capable of being ratcheted down should thejack stick when in load sustaininglposition; another object is theprovision in a jack of a centrifugal frictional controlcontion andtherebypermit the jack to auto-I` structed and arranged to automaticallygovern or uniformlyretard the descent of the jack under differing loadconditions by virtue ofthe variable centrifugal braking action setup insaid control rendering it adaptive to whatever loadis imposed upon it;

" a further object of mylinvention relatesto the provision of; driving`mechanism comprising leverage Increasing gearing` arranged intermediatethe operatingstub shaft of the ]ack and such control, whereby therotative speed of :the moving `partsof said control is materiallyincreasedover that of y saidshaft and :to therebyobtain a corre`spending leverage increment of `braking power at said shaft; a furtherobject ofthe inventionis to intermediately `provide said drivingrmechanismwithi` a positive acting` brake normally set tohold thejaclragainst involuntary descent `under load, said. brake being'manuallyreleasable to instantly bring1 matically descenduunder full `controlindependently of said brake; and afurtherobject of the invention `is to`so organize'the automatic control and the cooperating gearing withitspositive brakeso that theseparts together withthedetachable casingthat carries themlconstitute a self-contained mechanism, readilydetachable without disturbance of the partsfromthe supporting sleeve ofthe jack and asreadilyattachable.

`Speciiicafionof Letters Patent.

Patented Nov.15,192`1.

Application `iled March 8, 1919.` Serial No. 281,388.

These, together with such other advan tages as may be hereinafterdescribed, or

`are incident to my invention, I attain by means of a constructionillustrated in preferred form in the accompanying drawings. wherein: y i.Figure 1 represents a vertical sectional view of a jack to which myinvention is shown applied; y

Fig. 2 is a View taken along the line 2--2 of Fig. 1 looking in thedirection of the arrows, the lower partbeing in side eleva tionand theupper in partial cross-section;

Fig. 3 is a sectional view taken from the interior of the gear casingalong the line 3-3 of Fig. 1; and i Fig. 4 is a fragmentary View of aslightly modified .form of `the control illustrated more particularly inFigs. 1 and 3. Y

Referring to the drawings, the reference character` 5 denotes thestandard of the jack, and 6 designates the lifting sleeve movable'thereon and having as parts thereof the head cap 7 and the gear plate orcase 8. lVithin the upper end of the standardis mounted the usualoperating nut 9 carrying the lift'- ing screw 10 which is preferablypitched for a quick action lift. Keyed to the upper re-` duced end ofthe screw 10 is a bevel gear 11 having a meshed engagement with a bevelpinion 12 `whose operating shaft 13 is journaled in an extended bearing14 formed in the casing 8 and which vis terminally provided; with anysuitable operating mecha# nism, the `inner ratchet ortion only of whichis indicated at 15.` lVithin the head of the sleeve and between theopposed faces of the capand bevel gearl is a pair of superimposedbearing plates 16 and 17 provided intermediately with a seriesofant-friction members 18. The base of the j ack is desig nated by thereference character 19.

Before passing to a specific description of the preferred componentelements of the principal mechanisms involved in the invention, thefollowing brief Y localization of these mechanisms may be of assistancein` clarifying such description. letter A indicates a ratchetmechanismabout shaft 13 which idles during `the lifting action of the jaclr. butis brought into operation upon any reverse rotation of said brake B.`Upon release ofthe brake the soV The reference centrifugal control C,or C as modified in Fig. 4, comes into action to automatically governthe'descent of the jack under its load, and thereby prevents anydisability occurring to the jack which would be the case were itsdescent not retarded.

These, mechanisms are all associated and coperative, andas a wholeconstitute a complete geared device devoid of any need for manualadjustment to govern the selfloweringof the jack, the Agearing beingsuch as to multiply the leverage at mechanism C so that the increment ofsuch leverage is applied through mechanisms B and A to shaft 13 inasimple but very effective manner.

Similar characters designate like parts of these mechanisms throughoutthe several figures of the drawings.

The ratchet mechanism A consists of a ratchet 2O secured to the shaft 13to rotate with itiand a loose spur gea-r 21 providedwith spring pressedpawls 22 designed to ratchet idly over' the'teeth of the ratchet duringthe actuation ofthe shaft by the operating mechanism tolift the jack,and to engage them to impart motion to said gear 21 upon reverserotation'of the shaft under the influence oa load unless positivelychecked by the brake B. The ,i latter comprises a largefspur gear 23marginally flanged at one side to forman annular friction band 24 andintegrally provided on .the other side Y With a' small lpinion 25iii-mesh with the large spur gear 21, saidgear 23 and pinion 25being-loosely mounted for rotation about a stub shaft126 Whose outer end26 is threaded into an enlarged portion 8 of the casingSfgWithin thisband are apair of cams 27 and`28, the former axially mounted on a pins29threaded the casing 8, and being provided'vvith an arm 27 connectedtothe cam28 at'a point removed from its axis by-a link member 30, whichlatter has a tension springconnection 31 with the cam 28 lnormallyvacting to maintain the camming facesv incontact with the inner surfaceof the Aband at opposed points thereof.

' The cam28 is secured to the inner end of a fulcrum shaft 32 which isjournaled in said enlargementS and is extended therethrough to rigidlyca rry at its outer end a lever 33 having aterminal finger piece 34intermediate the guards 35 and 3G formed on the casing 8, the guard 36also constituting a fingerV piece when it is desired to manually dpress-th'elever iinger piece 34 to- Ward it and thereby release the brake sol lthat-the automatic control C may function.

This control C contemplates the provision of an annular friction band 37secured to an inner wall portion 6 of theV sleeve lin any suitablemanner concentric with the shaft 38, the latter'having its outer endfixed in a vhub portion 8a of the 'gear case and loosely carrying asleeve 39 which is formed with a Lof the disk are Weighted liber brakeshoes -l-.l

the weighted portions of which are lndir cated at 42. These shoes may heheld in position against the inner face of the band by the light helicalsprings 43 which extend between the lever arms 44 of the shoes and eyes45 provided on a small disk 46 secured to the sleeve. The tension of thespring preferably of a quality permitting the ratcheting down of thejack by the shaft operating mechanism 15 should the jack stick underload, and to permit the leverage increasing gearing to gain a promptstart upon release of the brake B. Instead of the springs 43, pins 43may be advantageously employed to approximately position the shoes, asindicated in Fig. 4 which illustrates a modified form of weighted leverbrake shoe embodying the short arm shoe 41', and the long lever arm 44which is provided with the'vveight 42. The pin 43 is so positioned thatwith the control at rest a slight clearance normally exists between theshoe and the band.

Obviously, the disk 40 of the control is the high speed member of themechanisms above described, and the centrifugal force present duringdisk rotation tends to throw the weighted brake shoes outwardly againstthe brake band 37, to frictionally retard the descent of the jacksleeve, the frictional braking effect correspondingly increasing to,counteract any increase in the rate of disk load conditions and therebyautomaticalli7 check such increase of speed. Stated di ilerently, thecentrifugal braking action of the control accommodates itself tovariable loads which may be sustained by the jack and. provides for asubstantially normal rate of selfloivering descent within the capacitylimit of the jack. Furthermore, it will be upparent that the leverageincrease obtained through the gearing multiplies the braking eflect'ofthe control to gain an increment of braking power at the operating shaft13, the lower speed member of the mechanisms. From the foregoing, itwill be seen that in the liftingv action of the jack these statedmechanisms are at rest, the positive brake serving to preventanyinvoluntary descent ofthe jack, release of which brake by depressingiinger piece 34 initiates the selflowering movement of the ack. Thismovement, as already set forth, is then wholly governed by the automaticcontrol, such control being characterized by an entire ab- `thesemechanisms proper, and their relation to gear case 8,1are along simpleand efficient lines, and as a whole the device takes upon itself a verycompact form inviting ease and economy in manufacture and the parts arereadily assembled and applied to the jack. With the single exception oftheV band 37, all the parts may be brought together as a self-containedunit carried by the casing 8, uncoupling of which permits the removal ofthe unit. Other advantages will readily appear to those skilled in theart.

I do not desire to be understood as limiting myself to the precisedetails `of construction, or to the exact arrangement of the variousparts or elements as shown` as it is manifest that variations and modiications thereof may be made without depart ing in any way from thespirit and scope of my invention and improvements, the instantembodiment of which is` illustrated in a preferred form. I thereforereserve the right to all such variations and modifications as properlyfall within the scope of my in vention and ,the terms of the followingclaims.

I claim: y

1. In a self-lowering lifting ack, the combination of af stationary memer, a lifting member movable thereon, a revoluble actuating membertherefor, a ratchet mechanism associated with said actuating member, alocking mechanism comprising a plurality of oscillatory cams for4releasably holding said liftin member against involuntary a descentunder load, an automatic controlling mechanism having a movable partthereof `constructed andarranged with reference to a fixed part thereofwhereby to centrifugally retard the descent of said lifting member uponrelease parts being disposed about a fixed axis of support on themovable member,

and said mechanisms associated in train by gearing designed to drivesaid movable part at a higher rate of speed than that of the revolubleactuating member.

2. In combinatioma casing, an actuating shaft therein having a ratchetmechanism including a loosely mounted .gear wheel, a pinion in meshtherewith provided with a 'spur gear having an annular band, a pluralityof lookin cams carried by said easing and normally ilicking with saidspur gear band, a shaft mounted in said casing and provided with asleeve having a pinion meshed with said spur gear, a fixed brake bandconcentric by said sleeve and pivotally provided near its margin with aplurality of lever brake of said locking mechanism, said withsaid shaft,a rotary disk carried shoes designed to flexibly engage said fixed lbrake ban as the disk rotates, said locking cams being provided with amanually operated lever extending through said casing.

3. In a jack, the combination of a support, an actuating shaft thereinhaving a ratchet mechanism including a loosely mounted gear wheel, apinion in mesh with said wheel, a spur gear connected to said pinion andprovided with an annular band, a plurality of locking cams arrangedwithin said banc, a spring for normally urging said cams into lockingrelation with said band, manual means for releasing said cams againstthe force of said spring, a sleeve mounted in said support and providedwith a pinion meshing with said spur gear, a stationary brake bandconcentric with said sleeve, a disk carried by the sleeve, a pluralityof brake shoes mounted on said disk and adapted to engage said band,centrifugally `actuated means for forcing said brake shoes intoengagement with said band, and a lifting member connected with saidshaft. i

4. In a lifting jack, the combination of a casing, a lifting membermovable therein, a rotatable shaft for actuating said member, ratchetmechanism connected with said shaft, locking mechanism for preventingreverse rotation of said shaft, comprising a pair of locking camsmounted in said casing, an annular rotatable band surrounding said camsand operatively connected with said shaft, means for normally urgingsaid cams into locking relation with said band, manual means forreleasing said cams, and a controlmechanism comprising a rotatable diskconnected to and adapted to be actuated bv rotation of said band, a.plurality of contri ugally-actuated brake shoes carried by said disk,and a stationary drum surrounding said brake shoes and adapted to beengaged thereby.

5. In a lifting jack, the combination of a i casing, a lifting membermounted therein, a shaft for actuating said member, a gear wheelsurrounding said shaft, pawl and ratchet connections between said wheeland said shaft., an annular drum adapted to be rotated by said gearwheel, a plurality of cams mounted within said drum, means for normallyurging said cams into locking relation with the drum, manual means forreleasing said cams, a disk connected to and adaptedto be rotated bysaid. drum, a plurality of centrifugally actuated brake shoes carried bysaid disk, and a stationarily mounted iannular drum surrounding saidshoes and adapted to be engaged thereby for controlling the speed ofrotation of said

